Processes for preparing flexible foams from polyols having a high oxyethylene (EO) content and a polyisocyanate having a high 4,4′-MDI content, have been disclosed in EP 547765. The examples shown in EP 547765 give low density foams with a low resilience, and no mouldings have been made.
Copending application EP 99105419.8 discloses a process for making a moulded polyurethane material, like a flexible polyurethane foam, by reacting 4,4′-diphenylmethane diisocyanate, a polyol having a high oxyethylene content and water. Repetitive mouldings can be made without the need to treat the mould for easy demoulding after every part has been made.
Surprisingly, it has now been found that if a polyol is used that has a high oxyethylene content and a high level of primary hydroxyl groups such easy demoulding is obtained as well, together with other good properties: load-bearing capacity, tear strength, creep properties, compression set and elongation and the foam has an improved resilience, especially at low density.